#include <iostream>
#include <cmath>
using namespace std;

class TwoCoor
{


public:
    float x,y;
    TwoCoor(int a,int b)
    {
        x=a;
        y=b;
    }

};
float dist(TwoCoor A,TwoCoor B)
{
    float d=sqrt(pow((A.x-B.x),2)+pow((A.y-B.y),2));
    return d;
}


int main(){
    TwoCoor p1(3,0),p2(0,4);
    cout<<dist(p1,p2);
    return 0;
}